The reactions of hemeproteins and molecular oxygen will be studied with an emphasis upon the mechanisms for reversible oxygen binding as in the hemoglobins and myoglobins, for oxygen reduction to water as in cytochrome c oxidase, and for hydroxylation reactions of the P450 cytochromes. Effects of abnormal protein structure and of agents such as anionic nucleophiles, "oxidant" drugs, anti oxidants, pollutants, and food additives on the production of superoxide, peroxide, and free radicals from hemoglobins and myoglobins, as well as the destructive action on cellular components by these products, will be studied. The mechanisms whereby the air pollutants CO and NO interfere with these systems will be investigated by infrared, electron spin resonance and other spectroscopic methods. Natural hemins and reconstituted hemeproteins will be utilized as models for the natural systems.